Cast metal articles



Patented Sept. 30, 1941 oA's'r METAL ARTICLES Hanley H. Weiser, Prince Bay, Staten Island,

N. Y., assignor to Nassau Smeltlng & Refining Company, Incorporated, New York, N. Y., a

corporation of New York Application October 31, 1939,

No Drawing.

Serial No. 302,119

. which render them especially suitable for mak- 3 Claims.

This invention relates to cast metal articles, and more particularly to articles cast from copper-tin-silicon alloys which are highly resistant to corrosion and also have unusually high elongations before rupture under high tensile stresses. a

Increasing efforts are being made, especially in industry based on chemical engineering procedures, to ensure safety in all possible ways.

' Apparatus employed in chemical industries particularly make extensive use of pipes and fittings, such as valves, which not only are normally subjectedto high pressure and the corrosive action of fluids passing through them, but which also may be subject to sudden and incalculable internal pressures of greater magnitude due to accidental stoppages, unintended chemical reactions, or other causes. Consequently a search has been made for materials for making such members, which shall not .only have high tensile strength and resistance to corrosion, but which shall also yield slowly and deform extensively before ultimate rupture under excessive tensile stresses, thus frequently perhaps relieving the stresses before rupture actually occurs.

' An object of the present invention is to provide cast articles having the properties of high tensile strength, high resistance to corrosion and unusually greatelongation before rupture when subjected to occasional high tensile stresses. With the above an other objects in view, the invention may be embodied in an article cast of an alloy consisting essentially of Per cent Silicon 2.00 to 3.75 Tin 0.25 to 1.50

variety of alloys having these and other metals 5 as constituents are known. These alloys frequently are satisfactorily corrosion resistant for inany uses in chemical industry but they lack some or'all of the desirable characteristics exhibited by th alloys of the present invention ing cast articles which may be subjected to sudden and large stresses.

Characteristics that are desirable in alloys for use in making cast products of this nature are fluidity when molten in order to cast well and especially to reproduce efiectively fine detail in the mold, low wetting power whenmolten in order that molding sand may not adhere to the solidified casting as it does with many bronze and brass alloys, the peculiar mixture of toughness and severability which renders the material machinable when solid, high tensile. strength, and, above all, a high degree of elongation before rupture under excessive tensile stresses.

It has been discovered that articles cast from an alloy of essentially the following basic composition possess the desired characteristics in an unusually high degree:

Minimum .Optimum Maximum Percent Percent I Percent Silicon 2.00 3. 3. 75 Tin; 0.25 1.00 1.50

and the balance copper except for insignificant amounts of other substances having no harmful effects.

Iron or manganese or both may be present in amount up to a total of 0.50% without mate-- rially affecting the. desirable properties either favorably or unfavorably. Cadmium and nickel are somewhat detrimental and should be held under 0.10% 'if present at all. Aluminum is detrimental in any amount and should therefore not be present.

The alloys described are remarkably fluid when molten and make clean, sharp castings free from adherent sand. They possess high tensile strength .and they are highly corrosion resistant, showing a possession of this characteristic, under test, to a somewhat higher degree than comparable alloys to be found generally available commercially. v

It is, however, in elongation before rupture under tensile stress that these alloys are particularly notable. Comparable commercial silicon bronzes show elongations generally of the order of 10% to 40%, with occasional specimens having elongations as high'as %,01 a little over, the tests being made on sand cast specimens and the elongations being measured over an original two inch length. But the particular alloys here in question show eldngations of which the following results, obtained in experimental tests, are typical:

In each case the balance of the alloy consisted of copper except for harmless impurities. Each of the above figures for tensile strength and elon-.

gation is the averageof tests on five separate specimens sand cast from the same melt, and tested without any heat treatment orother modification of the cast structure.

Apparently there is within a closely circumscribed and limited range of values of the silicon and tin in the series of ternary copper-silicon-tin alloys, the small group of alloys containing from about 2.00% to about 3.75% of silicon, from about 0.25% to about 1.50% of tin, and the balance, except for negligible impurities, copper, which group. exhibits elongations having values from two to four times as great as other Thus an alloy whose composition was Per cent Silicon- 3.20 Tin 1.12 Lead 0.24

, and the balance copper except for insignificant amounts of other harmless substances, showed,

as the average of five specimens, a tensile I ent discovery, the wholly unexpected and exalloys of similar composition. As noted above,

these elongations are shown by the alloys as cast in sand, without any special subsequent treatment such as annealing or other heat treatment to develop this character, and as measured over an original length of two inches. Hence, articles cast from the alloys will have these elongations without further treatment.

Cast articles embodying the invention will be of particular value when used under conditions where sudden shocks of considerable magnitude may be expected. Thus, for example, they are especially suited for the manufacture of pipes and fittings for apparatus to be used in chemical industry and which, by accident, may be subjected to excessive internal pressures. In suchcases, if these articles are cast from the alloys of the invention, they will yield slowly and extensively before finally rupturing and so may well prevent or at least minimize damage to their surroundings even if their own usefulness be destroyed. It will be, of course, necessary that such articles show a high degree of resistance to corrosion; and have high tensile strength and these particular alloys have these characteristics as well as the unusual high elongation and toughness.

So far the alloys of the invention have been considered as applied to the direct casting of articles to be usedwithout extensive further treatment. The alloys, however, are adaptable for use also where an article requiring considerable machining after casting is to be produced. 'While the alloys as described are machinable', they are somewhat diflicult to machine satisfactorily. It, has been found that their machinability may be improved by adding a small amount of lead thereto. When modified by the addition of not over about 0.5% and preferably about 0.25% of lead, they retain their toughness, strength and remarkable elongation, and in addition are freely machinable.

tremely useful properties of the specific alloys disclosed herein were entirely unknown. Furthermore, the peculiar value of cast articles and parts capable of being subjected to sudden tensile stress without rupture was also not known.

I In accordance with the invention, such articles are simply, cheaply and reliably mad by direct casting from these alloys without need for further apparatus or procedures for subsequent treatment. Since the invention is believed to reside only in cast articles made from the specific alloys and having the extraordinary prop-- erties described, no claim is as such. 1

It is, of course, to be understood that by'cast articles, as this term is used herein and in the made to the alloys annexed claims, is meant. articles having predetermined configurations which are designed to be utilized in the form in which they are cast for purposes where the peculiar and hitherto unknown properties of these alloys are especially desirable. It is not intended that the claims shall be interpreted to cover ingots, billets, bars, slabs or other shapes into which metals produced in bulk are formed for the purpose of providing masses which may be conveniently stored and handled and which are designed to be sub jected to further treatments or operations, such as rolling, forging, extrusion; drawing, etc., in

I which their shapes will be entirely altered.

What is claimed ,is:

l. Corrosion resistant. cast metal articles designed to be used as cast without further fabrication except machining, having elongations of upwards of 55% before rupture under tensile stress, and made of an alloy consisting of silicon 2.00% to 3.75%, tin 0.25% to 1.50%, and the balance substantially all copper.

2. Corrosion resistant, cast metal articles designed to be used as cast without further fabrication except machining, having elongations of upwards of 60% before rupture under tensile stress, and made of an alloy consisting of silicon about 3.25%, tin about 1.00%, and the balance substantially all copper.

3. Corrosion resistant, cast metal articles designed to be used as cast without further fabrication except machining, having. elongations of upwards of before rupture under tensile stress, and made of an alloy consisting of silicon about 3.50%, tin about 0.35%, and the balance substantially all copper.

HANLEY H. WEISER. 

